EQUILIBRIUM DISTRIBUTION OF PALLADIUM(II) BETWEEN HYDROCHLORIC-ACID SOLUTION AND A MACROMOLECULAR RESIN CONTAINING TRI-N-OCTYLAMINE

Studies have been conducted on the sorption characteristics of palladium(II) from hydrochloric acid media with a macromolecular rosin containing tri-n-octylamine (TOA). Sorption equilibrium of Pd(II) on the TOA-impregnated sorbent can be expressed by a simple ion-exchange reaction between a tetrachloro complex of Pd(II) in the aqueous phase and an amine salt in the sorbent as follows: 2R3NHClBAR + PdCl42- half arrow right over half arrow left (R3NH+)2PdCl42-BAR + 2Cl-where the equilibrium constant was found to be 6.98x10(4) kg/dm3. The elution of Pd(II) from the metal-loaded sorbent was also examined. Elution can be attained with either hydrochloric acid or aqueous ammonia: in particular, the latter gave a high elution ratio even at a concentration less than 1M. The effect of the pore diameter of the macromolecular resins on the Pd(II) sorption was also studied and two methods for preparating impregnated sorbent were examined.